Imaging of fetal GIT anomalies

IMAGING OF FETAL GIT ANOMALIES

IMAGING OF FETAL GIT ANOMALIES

PRESENTER : DR. DEEPAK GARG

the human embryo develops into a bilaminar disk of ectoderm and endoderm, with the endoderm forming the lining of the yolk sac. The endoderm is the scaffold for the future digestive tract.lateral folds , causing the endoderm to roll into a gut tube and pulling the amnionic cavity to surround the embryo. The head, tail and lateral folds draw the ventral body wall into a narrow region around the connecting stalk the umbilical ring . Note how the gut tube is pinched off from the yolk sac to form the narrow vitelline duct .

the human embryo develops into a bilaminar disk of ectoderm and endoderm, with the endoderm forming the lining of the yolk sac. The endoderm is the scaffold for the future digestive tract.lateral folds , causing the endoderm to roll into a gut tube and pulling the amnionic cavity to surround the embryo. The head, tail and lateral folds draw the ventral body wall into a narrow region around the connecting stalk the umbilical ring . Note how the gut tube is pinched off from the yolk sac to form the narrow vitelline duct .2

Stomach forms at about 4 weeks & descends into abdomen from initial position at about 7 weeksAbdominal wall muscles develop at about 11 weeksStomach can be seen on ultrasound at about as early as 7 weeks & should b routinely noted by 13 14 wks of gestation

CLASSIFICATION OF FETAL GI ANOMALIESesophageal atresia/ TEFduodenal atresia/ stenosisSmall-bowel atresiaMeconium ileusAnorectal atesiahepatomegalySplenomegalyOmphaloceleGastroschisisCystic anomalies like : choledochal cyst etc

ESOPHAGEAL ATRESIA TRACHEOESOPHAGEAL (TE) FISTULADefect : lack of development of the intermediate esophageal portion, mainly because of an interruption of the blood supply during organogenesis.Communication between the proximal and the distal tract of the esophagus is absentcan occur as an isolated anomaly (10% of cases) or, frequently, be associated with a (TE) fistula (90% of cases) VAC(TE)RL association

Defect : lack of development of the intermediate esophageal portion, mainly because of an interruption of the blood supply during organogenesis.25

Oesophageal atresia without fistula(blind pouches) 10% (TYPE A)

Proximal fistula with distal blind pouch 7 mm) of a single ileal/jejunal loop, possibly associated with a hyperechoic wall (arrowheads).

Ileal atresia. (a) Before 24 weeks of gestation, there is hardly any evidence of intestinal dilatation. The only doubtful sign isrepresented by a moderate dilatation (> 7 mm) of a single ileal/jejunal loop, possibly associated with a hyperechoic aspect of the wall (arrowheads).(b) In the 3rd trimester, the obstruction becomes evident, with moderately severe dilatation of various loops. In the dilated bowel loops cranialto the obstruction, increased intestinal peristalsis is seen, with the intestinal content moving from one loop to the adjacent one. (c) At 36 weeks, byfollowing the course of the dilated loops, it is possible to demonstrate the communication between the various dilated segments (the maximumtransverse diameter of the loops was 23 mm).48

ILEAL ATRESIA

24 weeks

30 weeks36 weeks(b) In the 3rd trimester, the obstruction becomes evident, with moderately severe dilatation of various loops. In the dilated bowel loops cranial to the obstruction, increased intestinal peristalsis is seen, with the intestinal content moving from one loop to the adjacent one.


ILEAL ATRESIA

24 weeks

30 weeks36 weeks. (c) At 36 weeks, by following the course of the dilated loops, it is possible to demonstrate the communication between the various dilated segments (the maximum transverse diameter of the loops was 23 mm).


ILEAL ATRESIA(a) Upright radiograph shows multiple air-fluid levels occupying the entire abdominal cavity. (b) Image from a barium enema study shows numerous dilated, air-filled loops of bowel and a small, unused colon (functional microcolon).

(a) Upright radiograph shows multiple air-fluid levels occupying the entire abdominal cavity. (b) Image from a barium enema study shows numerous dilated, air-filled loops of bowel and a small, unused colon (functional microcolon). 51

MECONIUM ILEUSMeconium ileus is characterized by an ileal mechanical obstruction caused by inspissated meconium,(the primary cause of which is cystic fibrosis)ETIOPATHOGENESIS : high protein content less fluids

significant inspissation blocks the intraluminal transit of the meconium

Intestinal obstruction perforation

MECONIUM PERITONITIS

The meconium is thicker than normal due to a high protein content, the primary cause of which is cystic fibrosis, associated with most cases of meconium ileus.This obstruction leads relatively often to ileal perforation and consequently meconium peritonitis.52

IMAGING multiple dilated loopshyperechoic content within gut loopshyperechoic wallsascitesDiffuse intra-abdominal calcifications

first evidence of meconium ileus at ultrasound consists of the so-calledHYPERECHOIC ILEUS

Meconium ileus. (a) At 29 weeks of gestation, some ileal loops are dilated and show hyperechoic walls (arrow). The presence of macrocalcifications (arrowheads) demonstrates the perforation and the consequent meconium peritonitis (b): an oblique view of the abdomen also demonstrates the presence of a secluded sac of ascites containing meconium sludge (arrow).

Meconium ileus. (a) At 29 weeks of gestation, some ileal loops are dilated and show hyperechoic walls (arrow). The presence ofmacrocalcifications (arrowheads) demonstrates the perforation and the consequent meconium peritonitis (c) The same case as in (b): an oblique view of the abdomen also demonstrates the presence of a secluded sac of ascites containing meconium sludge (arrow). (d) Another case showing diffuse intra-abdominal calcifications (arrows), consistent with a diagnosis of meconium peritonitis.54

(d) Another case showing diffuse intra-abdominal calcifications (arrows), consistent with a diagnosis of meconium peritonitis.

Meconium ileus. (a) At 29 weeks of gestation, some ileal loops are dilated and show hyperechoic walls (arrow). The presence ofmacrocalcifications (arrowheads) demonstrates the perforation and the consequent meconium peritonitis (c) The same case as in (b): an oblique view of the abdomen also demonstrates the presence of a secluded sac of ascites containing meconium sludge (arrow). (d) Another case showing diffuse intra-abdominal calcifications (arrows), consistent with a diagnosis of meconium peritonitis.55

ANORECTAL ANOMALIESTYPES :External : imperforate anus with/without fistula-Internal : pure rectal atresia and rectal atresia with fistulaMixed : ectopic anusAnorectal malformations can be divided, on the basis of their embryologic origin, into the following:EXTERNAL : due to abnormalities of the development and fusion of the external perineal layers.INTERNAL : developmental anomaly involves the primary partition of the cloaca by the urogenital septum.

Anorectal malformations can be divided, on the basis of their embryologic origin, into the following:EXTERNAL : due to abnormalities of the development and fusion of the external perineal layers.INTERNAL : developmental anomaly involves the primary partition of the cloaca by the urogenital septum.59

IMAGING : overdistended rectum & Sigmoid Colon with normal liquor.Liquor is decreased when associated with rectovesical fistula.rectal pouch is larger than full bladder, and with a bilobed appearance

Anorectal atresia. (a) Normal filling of the rectal pouch (arrow) behind the bladder (BI). (b) Evident dilatation of the rectum, which also shows hyperechoic content (arrows).

Anorectal atresia. (a) Normal filling of the rectal pouch (arrow), behind the bladder (BI). (b) Evident dilatation of the rectum, whichalso shows a hyperechoic content (arrows). (c) The fetus after termination of pregnancy. In addition to other anomalies, anorectal atresia wasconfirmed: the anal orifice is not visible61

(c) The fetus after termination of pregnancy. In addition to other anomalies, anorectal atresia was confirmed: the anal orifice is not visible

We should use probe of frequency less than 5 MHz. High frequency transducers give false positive results Echogenic bowel suggests bowel compromise. In approximately one third of fetuses with echogenic bowel on prenatal ultrasonography, a malformationof the GI tract is later confirmedDiagnosis is highly operator dependent

Iliac crest is used as an internal standard as it can usually be imaged at the same level as the bowel. Increasing echogenicity (and therefore a higher grade) correlates with increased risk of a fetal abnormalityA detailed ultrasound of the fetus should be performed (careful evaluation of the amniotic fluid, placenta, and membranes, for any features of intra-amniotic bleeding, such as particulate debris or clot floating in the amniotic fluid or chorioamniotic separation).

Iliac crest is used as an internal standard as it can usually be imaged at the same level as the bowel. Increasing echogenicity (and therefore a higher grade) correlates with increased risk of a fetal abnormalityA detailed ultrasound of the fetus should be performed (careful evaluation of the amniotic fluid, placenta, and membranes for any features of intra-amniotic bleeding, such as particulate debris or clot floating in the amniotic fluid or chorioamniotic separation).68

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FETAL CMV

Echogenic bowel in fetal CMV infection

Echogenic bowel in fetal CMV73

ANOMALIES OF ABDOMINAL WALL EMBRYOLOGY

ANOMALIES OF ABDOMINAL WALLOmphaloceleGastroschisisEctopia cordisCloacal exstrophylimbbodywall complex

OMPHALOCELEOmphalocele is a defect in the closure of the abdominal wall leads to herniation of abdominal visceraUSG : - bulging structure (i) arises from the anterior abdominal wall (ii) contains some abdominal viscera (liver and/or bowel) (iii) presents the cord insertion on its convexityAscitesPolyhydramnios

The presence of the umbilical vein within the omphalocele is an indirect sign of the fact that this anomaly represents a primary closure defect of the abdominal wall

Because of the limiting nature of these membranes, ascites is commonly visualizedThe herniated organs are wrapped in a two-layered sac, with the two layers being the peritoneum and the amnion.The cord insertion is located on the top of the sac. Two variants of omphalocele exist, according to the presence or absence of the liver in the sac.76

OMPHALOCELE

The herniated organs are wrapped in a two-layered sac, with the two layers being the peritoneum and the amnion.The cord insertion is located on the top of the sac. Two variants of omphalocele exist, according to the presence or absence of the liver in the sac.

At 23 weeks of gestation, the axial view of the abdomen demonstrates a large omphalocele containing the liver (the arrows indicate the large wall defect).

At 23 weeks of gestation, the axial view of the abdomen demonstrates a large omphalocele containing the liver (the arrows indicate the large wall defect).Midsagittal view of the abdomen: a case of omphalocele containing the liver at 29 weeks of gestation (normal karyotype). LIVER in herniated sac is sure short sign of omphalocoeleRarely, ascites can be associated with the omphalocele and can be detected in the sac (Asc); color Doppler shows the umbilical vein.78

Midsagittal view of the abdomen: a case of omphalocele containing the liver at 29 weeks of gestation (normal karyotype). LIVER in herniated sac is sure short sign of omphalocoeleRarely, ascites can be associated with the omphalocele and can be detected in the sac (Asc); color Doppler shows the umbilical vein.

DIFFERENTIAL DIAGNOSISphysiologic herniation in the cordgastroschisislimbbodywall complexcloacal exstrophyNormally physiological herniation gets corrected by 11 wks of gestation, If an omphalocele containing only ileal loops is identified earlier than the 12th week of gestation, the fetus should be rescanned in a weeks time: if the herniation persists, then it is an omphalocele

Normally herniation gets corrected by 11 wks of gestation, If an omphalocele containing only ileal loops is identified earlier than the 12th week of gestation, the fetus should be rescanned in a weeks time: if the herniation persists, then it is an omphalocele80

GASTROSCHISIS

Paraumbilical defect of the abdominal wall through which bowel loops herniate to float freely in the amniotic fluidEtiopathogenesis : - abnormal regression of the right UV - vascular accident during embryogenesisUSG : - freely floating bowel outside the fetal abdomen - identification of the right para-umbilical wall defect - Normal cord insertion. - thickening and edema of the intestinal walls with signs of obstruction

herniated viscera consist, in the overwhelming majority of cases, of bowel loops only; in very rare circumstances, the stomach and, exceptionally, urogenitalstructures may herniate as well. As already pointed out, there is no membrane wrapping the herniated viscera, as in omphalocele, and these float freely in the amniotic fluid.defect is small (< 2 cm),& this is responsible for occurrence of bowel infarction due to torsion and/or compression of the mesenteric pedicle on the rim of the defect81

GASTROSCHISIS

herniated viscera consist, in the overwhelming majority of cases, of bowel loops only; in very rare circumstances, the stomach and urogenital structures may herniate as well. As already pointed out, there is no membrane wrapping the herniated viscera and these float freely in the amniotic fluid.defect is small (< 2 cm),& this is responsible for occurrence of bowel infarction due to torsion and/or compression of the mesenteric pedicle on the rim of the defect

Gastroschisis at 16 weeks of gestation. showing the bowel loops floating freely in the amniotic fluid

Gastroschisis at 16 weeks of gestation. (a) showing the bowel loops floating freely in the amniotic fluidB) Gastroschisis at 31 weeks of gestation. The appearance of bowel dilatation in the 3rd trimester represents a complication, indicatinga likely obstruction. This situation may evolve with perforation and/or necrosis of one or more bowel loops. (a) Sagittal view of the fetal trunk showing some normally sized loops close to the fetal arm and one severely dilated tract (arrow). (c) Axial view demonstrating also some meconium blocked in the dilated loop (arrowhead).83

Gastroschisis at 31 weeks of gestation. The appearance of bowel dilatation in the 3rd trimester represents a complication, indicating a likely obstruction. This situation may evolve with perforation and/or necrosis of one or more bowel loops.

Axial view demonstrating some meconium blocked in the dilated loop (arrowhead).

LIMBBODYWALL COMPLEX

Limbbody wall complex consists of a variable groups of congenital limb and body wall defects of the chest and abdomen

a) Free floating complex mass containing liver with short umbilical cord originating from the placenta to the mass

Limbbody wall complex consists of a variable group of congenital limb and body wall defects of the chest and abdomena. Free floating complex mass containing liver (*) with short umbilical cord (arrow) originating from the placenta to the massb. Free floating complex mass containing liver (*) with covering membrane (arrowhead), short umbilical cord (arrow) originating from the placenta to the mass86

LIMBBODYWALL COMPLEX

Coronal MR images show large anterior abdominal wall defect (arrows) with liver (L) and bowel (B) attached to placenta (P).Sagittal MR image shows heart (H), liver (L), and bowel (arrows) protruding through anterior abdominal and chest wall defect.

Coronal MR images show large anterior abdominal wall defect (arrows) with liver (L) and bowel (B) attached to placenta (P).Sagittal MR image shows heart (H), liver (L), and bowel (arrows) protruding through anterior abdominal and chest wall defect.87

PENTALOGY OF CANTRELL

Pentalogy of Cantrell : omphalocele, ectopia cordis, diaphragmatic defect, pericardial defect, and cardiovascular malformationThe cause of pentalogy of Cantrell is failure of the lateral body folds to fuse in the thoracic region, with variable extension inferiorly

The cause of pentalogy of Cantrell, failure of the lateral body folds to fuse in the thoracic region, with variable extension inferiorlyTransverse sonogram of another case demonstrates the nearly complete exteriorization of the heart (arrow). The other features of pentalogy of Cantrell (see text)were present in both cases but are not shown. (13) Pentalogy of Cantrell. Longitudinal sonogram shows a large omphalocele (arrowheads) extendingcephalad to involve the region of the sternum. Ectopia cordis was also present.88

Transverse sonogram demonstrates the nearly complete exteriorization of the heart (arrow).Longitudinal sonogram shows a large omphalocele (arrowheads) extendingcephalad to involve the region of the sternum. Ectopia cordis was also present.

CLOACAL EXSTROPHY

Failure to visualize the bladder in the pelvis. Sagittal view of the lower body, showing the omphalocele (arrowheads) and the bladder exstrophy (arrows).

Failure to visualize the bladder in the pelvis. Presence of a small mass on the lower abdominal wall(bladder exstrophy). Ample abdominal wall defect with presence of omphalocele or cystic anterior abdominal wallstructure in contact with the amniotic fluid (cloacal exstrophy(b) Sagittal view of the lower body, showing the omphalocele(arrowheads) and the bladder exstrophy (arrows).90

HEPATOMEGALY(HEPATITIS)

Causes

Intrauterine fetal infections( CMV) ,hepatitis are among the most common causes of hepatosplenomegalyDown syndrome may be responsible, in some cases, for moderate to severe hepatomegaly.Rare benign and malignant hepatic tumors, such as hemangioma or hepatoblastoma.fetal anemiaBeckwithWiedemann and Zellweger syndromes

Intrauterine fetal infections( CMV) ,hepatitis are among the most common causes of hepatosplenomegalyDown syndrome may be responsible, in some cases, for moderate to severe hepatomegaly. Also, rare benign and malignant hepatic tumors, such as hemangioma or hepatoblastoma,, fetal anemia may induce hepatomegalyBeckwithWiedemann and Zellweger syndromes, that can be associated with hepatomegaly.Hepatomegaly. This patient had had serologically confirmed hepatitis A infection in the 1st trimester. At 19 weeks, ultrasound demonstrated the following: (a) Axial view: evident hepatomegaly, with capsular macrocalcification and moderate ascites. (b) Left parasagittal view: The ascites and moderate enlargement of the left hepatic lobe (LL, arrowheads) are shown; in such a situation, the left hepatic lobe should not be mistaken for the spleen, CAREFUL ASSESSMENT SHUD B DONE TO R/O CALCIFICATION OF MECONIUM PERITONITIS OR PARENCHYMAL CALCIFICATION93

Hepatomegaly. This patient had serologically confirmed hepatitis A infection in the 1st trimester. At 19 weeks, ultrasound demonstrated the following: (a) Axial view: evident hepatomegaly, with capsular macrocalcification and moderate ascites. (b) Left parasagittal view: The ascites and moderate enlargement of the left hepatic lobe (LL, arrowheads) are shown; in such a situation, the left hepatic lobe should not be mistaken for the spleen.

HEPATOMEGALY( CMV)

Severe hepatomegaly due to CMV infection. on the axial view of the upper abdomen, it is possible to recognize the enlarged, hyperechoic, and rather inhomogeneous liver (arrows). On the right parasagittal view, the degree of hepatomegaly is easily evaluated and the prominence of the abdomen in comparison with the normal thorax is evident (arrowheads

Severe hepatomegaly due to CMV infection. (a) on the axial view of the upper abdomen, it is possible to recognize the enlarged, hyperechoic, and rather inhomogeneous liver (arrows). (b) On the right parasagittal view, the degree of hepatomegaly is easily evaluated and the prominence of the abdomen in comparison with the normal thorax is evident (arrowheads95

INTRAHEPATIC CALCIFICATIONS

A and b show calcification in the fetal liver. The maternal history was unremarkable, and the outcome was normal.

C and D show diffuse punctate calcifications in fetal liver.an infectious cause was thought to be likely.

Intrahepatic calcifications. (a, b) Axial (a) and oblique coronal (b) sonograms obtained at 18 weeks gestationshow calcification in the fetal liver. The maternal history was unremarkable, and the outcome was normal.(c, d) Axial sonograms of the liver of another fetus, obtained at 20 weeks gestation, show diffuse punctate calcifications.Results of testing for cytomegalovirus were indeterminate twice, and an infectious cause was thought to belikely. The neonatal outcome was normal.96

SPLENOMEGALY

Splenomegaly in two cases of severe fetal CMV infection. (a) On the coronal view, at 37 weeks of gestation, it is possible to recognize the severely enlarged spleen (Spl), the lower pole of which reaches the bladder (Bl) and a concurrent similarly severe hepatomegaly (Li). (b) A similar case, at 36 weeks of gestation, showing severe hepatosplenomegaly, ascites, and intra-abdominal calcifications. Both neonates died of widespread CMV infection.

Splenomegaly in two cases of severe fetal CMV infection. (a) On the coronal view, at 37 weeks of gestation, it is possible to recognize the severely enlargedspleen (Spl), the lower pole of which reaches the bladder (Bl) and a concurrent similarly severe hepatomegaly (Li). (b) A similar case, at 36 weeks of gestation, showing severe hepatosplenomegaly, ascites, and intra-abdominal calcifications. Both neonates died of widespread CMV infection.97

FETAL GALLSTONES

Fetal gallstones. (a) Coronal sonogram obtained at 16 weeks gestation shows shadowing stones in the fetal gallbladder.

Postulated causes of fetal gallstones include hemolytic disease, cholestasis, and maternal drug use. These stones resolve immediately in post natal life.

Fetal gallstones. (a) Coronal sonogram obtained at 16 weeks gestation shows shadowing stones in the fetal gallbladder.Gallstones and gallbladder sludge (thickened bile containing a precipitation of calcium, pigment, and cholesterol elements)Postulated causes of fetal gallstones include hemolytic disease, cholestasis, and maternal drug use. These stones resolve immediately in post natal life.98

NEUROBLASTOMA

Neuroblastoma with hemorrhage in fetus at 34 weeks' gestational age referred for evaluation of right suprarenal mass. Coronal sonogram of fetal abdomen shows complex mass (arrow) above right kidney (arrowheads). No normal adrenal tissue is identified.Sagittal MR shows hyperintense well-demarcated lesion (arrow) above right kidney (arrowheads).

Neuroblastoma with hemorrhage in fetus at 34 weeks' gestational age referred for evaluation of right suprarenal mass. Coronal sonogram of fetal abdomen shows complex mass (arrow) above right kidney (arrowheads). No normal adrenal tissue is identified. Neuroblastoma with hemorrhage in fetus at 34 weeks' gestational age referred for evaluation of right suprarenal mass. Sagittal mr shows hyperintense well-demarcated lesion (arrow) above right kidney (arrowheads).99

CONCLUSION A wide spectrum of abdominal anomalies can be seen in utero.Look for any systemic involvementMost of GI anomalies show similar features like cysts, abdominal wall defectsFollow up of growth & assessment of progression of bowel obstruction is important in atresiasMRI is problem solving tool.

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Imaging of fetal GIT anomalies